1. Field of the Invention
The present invention relates to a pressure release mechanism, and more particularly to a pressure release mechanism that is simple in structure and reliable at great pressure. The pressure release mechanism uses pressure difference to move a activating piston to release the restrain on balls received in the head, which disconnect the engagement between the head and the body to perform the desired purpose.
2. Description of Related Art
Currently, to deploy a sensitive or fragile object in the water, a cable with a hook attached to the free end of the cable is used to lift the object into the air and then lower the object into the water. When the object reaches a predetermined depth, divers or other auxiliary equipment or facilities are required to release the object from the hook, which will either endanger the divers because of the water pressure or not be cost effective because of the equipment or facilities required.
To overcome the problems, another release device was introduced. With reference to FIG. 5, the release device has a body (70) with a chamber (71) defined inside the body (70). The chamber (71) movably houses receiving a driving rod (72) and a driven rod (74). A recess (741) is defined in the driven rod (74) to receive the head (721) of the driving rod (72). Multiple notches (742) are defined in the inner surface defining the recess (741) to receive a ball (75) in each notch (742). The diameter of the head (721) is larger than the diameter of the driving rod (72), such that when the head (721) is in the recess (741), the outer periphery of the head (721) abuts the balls (75) that are securely held in the respective notches (742). A diaphragm (731) is mounted on the end of the chamber at the free end of the driving rod (72) and is securely held in place by a cover (73). The cover (73) has multiple openings (732) defined to allow the external environment to communicate with the diaphragm (731). A first hook (701) is integrally formed on the body (70), and a second hook (702) is pivotally engaged with the first hook (701) to form an eye. A lever arm (703) extends from the bottom of the second hook (702) and is in contact with the free end of the driven rod (74). The free end of the driven rod (74) held in position by the balls (75) in the notches presses the extension (703) and holds the first and second hooks (701,702) to keep the eye closed.
When the conventional release mechanism is lowered into the water, water enters the openings (732) and exerts pressure on the diaphragm (731). As the water depth increases, the water pressure acting on the diaphragm (731) causes the diaphragm (731) to deform and press against the distal end of the driving rod (72). When the driving rod (72) is displaced enough by the water pressure pressing on the diaphragm (731), the head (721) moves into the recess (741) and releases the balls (75) in the notches (742). This releases the force holding the free end of the driven rod (74) against the extension (703) on the second hook (702). The second hook (702) then pivots relative to the first hook (701), opens the eye and releases the chain (80) that was held in the eye. Releasing the chain (80) deploys the object attached to the pressure release device in the water.
Since the release mechanism is attached to the object deployed in the water likely not to be recovered for use again, the cost of fabrication and the complex structure of the release mechanism do not appear to be warranted. Furthermore, movement of the balls (75) to allow the movement of the driven rod (74) to release the second hook (702) is an incidental rather than an initiated action. It may happen when the head (721) is pushed into the recess (741), and it may not. Virtually any obstruction of the second hook (702), the driving rod (72) or the extension (703) would cause the release device to fail to operate as intended. The diaphragm (731) is always a potential source of failure in a pressure device. A crack in the diaphragm (731) due to high pressure, testing or maintenance will cause the release device to fail. Improper seating of the diaphragm and sealing of the chamber (71) will also cause the release device to fail.
To overcome the shortcomings, the present invention tends to provide an improved pressure release mechanism to mitigate and obviate the aforementioned problems.